Analysis Of Cracking And Recrystallization For A DCO4Steel During Hot Rolling

DC04steel has been widely used in automotive, appliance, chemical industry,construction industry, metallurgical industry for its excellent stamping performanceand beautiful appearance. In the production process of DC04steel, the hot rollingprocess is very important for influencing the production quality and the finalperformance of DC04. During hot rolling, dynamic recrystallization and staticrecrystallization occur and affect the final grain size and texture distribution, thendecide the hot working performance, subsequently process and the final stampingperformance. Therefore, the study of dynamic recrystallization and staticrecrystallization of DC04steel is very important for guiding the improvement of newsteel grades and the development of hot rolling process, with great theoretical andengineering significance. In this thesis, the hot rolling process of DC04was simulatedby Gleeble-1500thermo-mechanical simulator, which was used to study the behaviorof recrystallization. The influence of rolling temperature, reduction rate and holdingtime on recrystalliztion was studied.The hot rolling cracks of DC04steel are edge crack, strip crack and warping. Slabdefects (eg bubbles, micro-cracks, etc.), inclusions, grain burnt, abnormal carboncontent, tilt, induce the hot rolling cracks.When compressing with a strain rate10s-1, the main performance is work hardenand dynamic recovery. When compressing with a strain rate5s-1, obvious dynamicrecrystallization occurs at temperature between1000and1100℃, while work hardenand dynamic recovery is the main performance between900and950℃.Whencompressing with a strain rate0.1s-1, dynamic recrystallization occurs at all the testtemperature between850to1100℃, and multi-peak of dynamic recrystallizationexists on stress-strain curves between900to1000℃. Then activation energy ofrecrystallization was calculated to be125.8kJ/mol and the figures of recrystallizationregions distribution was shown at last.Holding20seconds following the compressing at1050℃and950℃increases the recrystallization fraction up to90percent.